Thermal interface apparatus, systems, and fabrication methods

ABSTRACT

A method and machine may operate to fabricate a unitary, substantially uniformly distributed transfer material that can be coupled to a carrier material.

This application is a divisional of U.S. patent application Ser. No.11/368,708, filed on Mar. 6, 2006, which is a divisional of U.S. patentapplication Ser. No. 10/608,519, filed on Jun. 24, 2003, now issued asU.S. Pat. No. 7,042,729, which are both incorporated herein byreference.

BACKGROUND INFORMATION

Electronic components, including integrated circuits, may be assembledinto component packages by physically and electrically coupling them toa substrate. During operation, the package may generate heat that can bedissipated to help maintain the circuitry at a desired temperature. Heatsinks, heat spreaders, and other heat dissipating elements may beattached to the package using a suitable thermal interface material.

The interface material, which may take the form of Indium-based solderpaste, can be used to attach a copper heat spreader to a die, forexample. However, the paste typically includes solder particles ofwidely variable size, resulting in non-uniform distribution of particlesacross the die, high thermal resistance, and mechanical stress.Different interface materials, or arrangements of such materials, mayoperate to improve heat transfer from sources, such as dice, to sinks,such as heat spreaders.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are top cut-away and side cut-away views, respectively,of an apparatus according to various embodiments;

FIGS. 2A and 2B are top cut-away and side cut-away views, respectively,of an apparatus according to various embodiments;

FIG. 3 is a side cut-away view of an apparatus and a system according tovarious embodiments;

FIG. 4 is a side view of a machine according to various embodiments; and

FIG. 5 is a flow chart illustrating several methods according to variousembodiments.

DETAILED DESCRIPTION

In the following detailed description of various embodiments, referenceis made to the accompanying drawings that form a part hereof, and inwhich are shown by way of illustration, and not of limitation, specificembodiments in which the subject matter may be practiced. In thedrawings, like numerals describe substantially similar componentsthroughout the several views. The embodiments illustrated are describedin sufficient detail to enable those skilled in the art to practice theteachings disclosed herein. Other embodiments may be utilized andderived therefrom, such that compositional, structural, electrical, andlogical substitutions and changes may be made without departing from thescope of this disclosure. The following detailed description, therefore,is not to be taken in a limiting sense.

FIGS. 1A and 1B are top and side cut-away views, respectively, of anapparatus 100 according to various embodiments. The apparatus 100 may beused to assist in transferring heat from one element or body, such as acircuit or die, to another, such as a heat sink, for example. Theapparatus 100 may comprise a unitary, substantially uniformlydistributed transfer material 110 forming a mesh and coupled to acarrier material 120. The unitary, substantially uniformly distributedtransfer material 110 may comprise at least one of a component transfermaterial 124, including bismuth, copper, gold, indium, zinc, antimony,magnesium, lead, silver, tin, and alloys thereof. The carrier material120 may comprise at least one of a component carrier material 128including a polymer, an elastomer, a hardener, a catalyst, a reactivediluent, an adhesion promoter, a surfactant, a deforming agent, afluxing agent, a toughening agent, a coupling agent, an epoxy, an ester,a siloxane, a polyamide, a silicone, a rubber, and a wetting agent.

It should be noted that the component transfer material 124 and thecomponent carrier material 128 are shown as discrete components of theunitary, substantially uniformly distributed transfer material 110 andthe carrier material 120, respectively, in FIGS. 1A and 1B. This methodof illustration is used so as not to obscure the makeup of the materials110, 120, but is not meant to limit the use, appearance, form, orcombinational mechanisms of the materials 110, 120 in any way.

A plurality of elements 132 may be included in the unitary,substantially uniformly distributed transfer material 110, forming aportion of the mesh. The elements 132 may be distributed in asubstantially repetitive pattern, such as a substantially parallelpattern, including a grid pattern (i.e., two substantially parallelpatterns juxtaposed to each other in a substantially perpendicularfashion), as shown in FIG. 1A. Thus, the unitary, substantiallyuniformly distributed transfer material 110 may include elements 132,forming a portion of a mesh, which may in turn comprise a plurality ofsubstantially similar geometric objects, perhaps arranged in asubstantially repeating pattern.

The elements, 132, including a plurality of substantially similargeometric objects, may comprise a plurality of regular geometricobjects, such as a sphere, a spherical cap, a torus, a rectangularparallelepiped, a cube, a pyramid, a cylinder, a frustrum, an ellipsoid,an elliptic cylinder, an elliptic cone, an elliptic hyperboloid, aparaboloid of revolution, and/or a hyperbolic paraboloid. Alternatively,or in addition, the elements 132, including a plurality of substantiallysimilar geometric objects, may include a plurality of irregulargeometric objects, which can be patterned (e.g., figurines, animals,trees, holiday shapes, stars, pillows, twists, wagon wheels, etc.) orunpatterned.

Many of the geometric objects, including combinations of regular andirregular geometric objects (e.g., crab, palm tree, and bird), can beinterlocked together or tessellated such that when cut from a singlesheet, there is minimal waste. The height, shape, and/or spacing of theplurality of substantially similar geometric objects can be selectedbased on a desired volume of the unitary, substantially uniformlydistributed transfer material 110 within the carrier material 120,and/or a desired thickness T of the apparatus 100.

A plurality of connecting elements 136 included in the unitary,substantially uniformly distributed transfer material 110 may be used tocouple the elements 132, including the plurality of substantiallysimilar geometric objects to each other. The plurality of connectingelements 136 may also be arranged in a substantially repeating pattern.

In another embodiment, the apparatus 100 may be described as including acarrier material 120 and a solderable transfer material 110 at leastpartially embedded within the carrier material 120 and arranged in asubstantially uniform fashion. The solderable transfer material 110 maycomprises at least one of a component transfer material 124 includingbismuth, copper, gold, indium, zinc, antimony, magnesium, lead, silver,tin, and alloys thereof. The solderable transfer material may alsocomprise a plurality of elements 132, each including one or moresubstantially similar geometric objects distributed on substantiallyrepeating pattern, such as a substantially parallel pattern, including agrid pattern.

As noted previously, the substantially similar geometric objects mayinclude a plurality of regular geometric objects, and/or a plurality ofirregular geometric objects. The apparatus 100 may also comprise aplurality of connecting elements 136 to couple the plurality elements132, each including one or more substantially similar geometric objects,to each other.

In yet another embodiment, an apparatus 100 may be described ascomprising an array 110 of solderable elements 132 coupled to each otherby a plurality of solderable connecting elements 136. The apparatus 100may also include a carrier material 120 coupled to the array 110 ofsolderable elements 132. The array 110 of solderable elements 132 may befully or partially embedded in the carrier material 120.

Many choices can be made regarding the size and shape of the solderableelements 132, including selecting an average volume of each one of theplurality of solderable connecting elements 136 to be less than aboutone-half of the volume of an average size of each one of the solderableelements 132 in the array 110. The height, shape, and/or spacing of theplurality of solderable elements 132, including substantially similargeometric objects, may be selected based on an associated package stress(as described hereinbelow).

The appearance and arrangement of the apparatus 100 in FIGS. 1A and 1Bis shown after manufacture, and before use in various applications. Insome embodiments, where the apparatus 100 is applied between a die and aheat spreader for example, a preform cure stage may be used to alter thestructure of the apparatus 100. For example, after the apparatus 100 isinserted between a die and a heat spreader, and heat is applied to thecombination, the apparatus 100 may appear as shown in FIGS. 2A and 2B,which are top cut-away and side cut-away views, respectively, of anapparatus 200 according to various embodiments. In this case, some orall of the connecting elements 236 may be missing because they havemelted due to the application of heat to the apparatus 200, and becomeincorporated into the elements 232, which in turn have formed flattenedspheres (when placed between a die and a heat spreader, for example, asshown in FIG. 3). In fact, selected ones of the connecting elements 236may be eliminated from the apparatus 200 as desired by the designer andappropriate to a particular application, either during manufacture, orduring/after use in a particular application. Thus, in some embodiments,a continuous solder mesh 110 (see FIG. 1A) can be transformed into anarray of elements 232, each including one or more solder particles (seeFIG. 2A) embedded in a carrier material 220 during a perform cure stage.

Still other embodiments may be realized. FIG. 3 is a side cut-away viewof an apparatus 300 and a system 350 according to various embodiments.For example, a system 350 may comprise a wireless transceiver 354, a die358 including a circuit 362 coupled to the wireless transceiver 354, anda unitary, substantially uniformly distributed transfer material 310forming a mesh, and coupled to a carrier material 320 and adjacent thedie 358.

As noted previously, the plurality of 332, including geometric objects,which may be substantially similar, included in the unitary,substantially uniformly distributed transfer material 310 may form aportion of a mesh and be distributed in a substantially repeatingpattern. A plurality of connecting elements 336 may be used to couplethe plurality of elements 332 included in the unitary, substantiallyuniformly distributed transfer material 310 to each other. Thesubstantially repeating pattern may comprise a parallel pattern,including a grid pattern.

The system 350 may also comprise a heat dissipating element 364 coupledto the unitary, substantially uniformly distributed transfer material310. The heat dissipating element 364 may comprise any number ofdevices, including a heat sink, a peltier cooler, and/or a heatspreader. The die 358 may comprise any kind or amount of circuitry 362and/or components, including a flip-chip, a processor, one or more powertransistors, and/or a memory. The height, shape, and/or spacing of theplurality of elements 332, including objects, such as geometric objects,may be selected based on a package stress associated with the die 358.

The die 358 and the wireless transceiver 354 may be coupled to asubstrate 366, which may comprise organic or inorganic materials, orcombinations of these. The substrate 366 may also comprise flexiblematerials and/or nonflexible materials. Materials included in thesubstrate 366 may be non-conductive or conductive, depending upon theconfiguration and requirements of the apparatus 300 and system 350.

Still other embodiments may be realized. FIG. 4 is a side view of amachine 474 according to various embodiments. The machine 474 maycomprise one or more transport elements 478 and a pair of rollers 482,at least one of which is capable of being coupled to a transport element474. One or more of the rollers 482 may comprise a pattern to form acorresponding pattern in a solderable material 410. The pattern mayinclude an array of elements 432, including geometric objects, arrangedin a substantially repetitive manner, including as a plurality ofsubstantially similar geometric objects distributed on a grid pattern,as shown for elements 132 in FIG. 1A. Selected elements 432 included inthe array of elements 432 may be interconnected by a plurality ofconnecting elements 436.

It should also be understood that the apparatus and systems of variousembodiments can be used in applications other than for coupling and heattransfer between dice and heat dissipating elements, and thus, theembodiments shown are not to be so limited. The illustrations ofapparatus 100, 200, 300, and a system 350 are intended to provide ageneral understanding of the elements and structure of variousembodiments, and they are not intended to serve as a completedescription of all the features of apparatus and systems that might makeuse of the elements and structures described herein.

Applications that may include the novel apparatus and systems of variousembodiments include electronic circuitry used in high-speed computers,communication and signal processing circuitry, data transceivers,modems, processor modules, embedded processors, and application-specificmodules, including multilayer, multi-chip modules. Such apparatus andsystems may further be included as sub-components within a variety ofelectronic systems, such as televisions, cellular telephones, personalcomputers, workstations, radios, video players, vehicles, and others.

Some embodiments include a number of methods. For example, FIG. 5 is aflow chart illustrating several methods according to variousembodiments. Thus, a method 511 may (optionally) begin with forming aunitary, substantially uniformly distributed transfer material as a meshat block 521, and coupling a carrier material to the unitary,substantially uniformly distributed transfer material at block 535.

Forming the unitary, substantially uniformly distributed transfermaterial as a mesh at block 521 may further comprise impressing at leastone patterned roller against a sheet of solderable material. Embossing,printing, laminating and punching may also be used. Coupling the carriermaterial to the unitary, substantially uniformly distributed transfermaterial may include curing the carrier material. The carrier material,which may comprise a polymer, may be laminated or coated onto theunitary, substantially uniformly distributed transfer material. Otherprocesses may also be used, such that the unitary, substantiallyuniformly distributed transfer material is partially or fully embeddedin the carrier material.

The method 511 may also include placing the unitary, substantiallyuniformly distributed transfer material and the carrier material betweena die and a heat dissipating element at block 561, and heating theunitary, substantially uniformly distributed transfer material so as tobreak a selected number of connecting elements coupling a plurality ofgeometric objects included in the unitary, substantially uniformlydistributed transfer material at block 571.

It should be noted that the methods described herein do not have to beexecuted in the order described, or in any particular order. Moreover,various activities described with respect to the methods identifiedherein can be executed in serial or parallel fashion.

Although specific embodiments have been illustrated and describedherein, it should be appreciated that any arrangement calculated toachieve the same purpose may be substituted for the specific embodimentsshown. This disclosure is intended to cover any and all adaptations orvariations of various embodiments. It is to be understood that the abovedescription has been made in an illustrative fashion, and not arestrictive one. Combinations of the above embodiments, and otherembodiments not specifically described herein will be apparent to thoseof skill in the art upon reviewing the above description. Thus, thescope of various embodiments includes any other applications in whichthe above compositions, structures, and methods are used.

It is emphasized that the Abstract of the Disclosure is provided tocomply with 37 C.F.R. §1.72(b), requiring an abstract that will allowthe reader to quickly ascertain the nature of the technical disclosure.It is submitted with the understanding that it will not be used tointerpret or limit the scope or meaning of the claims. In addition, inthe foregoing Detailed Description, it can be seen that various featuresare grouped together in a single embodiment for the purpose ofstreamlining the disclosure. This method of disclosure is not to beinterpreted as reflecting an intention that the claimed embodimentsrequire more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive subject matter lies in lessthan all features of a single disclosed embodiment. Thus the followingclaims are hereby incorporated into the Detailed Description, with eachclaim standing on its own as a separate preferred embodiment.

1. A method, comprising: forming a unitary, substantially uniformlydistributed transfer material as a mesh including a plurality geometricobjects forming a substantially repeating pattern; and coupling acarrier material to the unitary, substantially uniformly distributedtransfer material.
 2. The method of claim 1, wherein forming theunitary, substantially uniformly distributed transfer material furthercomprises: impressing at least one patterned roller against a sheet ofsolderable material.
 3. The method of claim 1, wherein forming theunitary, substantially uniformly distributed transfer materialcomprises: forming the unitary, substantially uniformly distributedtransfer material comprising at least one of a component transfermaterial including bismuth, copper, gold, indium, zinc, antimony,magnesium, lead, silver, tin, and alloys thereof.
 4. The method of claim1, wherein forming the unitary, substantially uniformly distributedtransfer material comprises: forming the unitary, substantiallyuniformly distributed transfer material with the plurality of geometricobjects distributed on a grid pattern.
 5. The method of claim 1, whereinforming the unitary, substantially uniformly distributed transfermaterial comprises: forming the unitary, substantially uniformlydistributed transfer material including a plurality of connectingelements to couple the plurality of geometric objects to each other. 6.The method of claim 5, wherein the plurality of connecting elements arearranged in a substantially repeating pattern.
 7. The method of claim 1,wherein the plurality of geometric objects includes a plurality ofregular geometric objects.
 8. The method of claim 1, wherein theplurality of geometric objects includes a plurality of irregulargeometric objects.
 9. The method of claim 1, comprising: selecting atleast one of a height, a shape, and a spacing of the plurality ofgeometric objects based on a desired volume of the unitary,substantially uniformly distributed transfer material.
 10. The method ofclaim 1, wherein coupling the carrier material comprises: coupling thecarrier material comprising at least one of a component carrier materialincluding a polymer, an elastomer, a hardener, a catalyst, a reactivediluent, an adhesion promoter, a surfactant, a deforming agent, afluxing agent, a toughening agent, a coupling agent, an epoxy, an ester,a siloxane, a polyamide, a silicone, a rubber, and a wetting agent. 11.The method of claim 1, wherein coupling the carrier material comprises:curing the carrier material.
 12. The method of claim 1, wherein couplingthe carrier material comprises: at least partially embedding theunitary, substantially uniformly distributed transfer material in thecarrier material.
 13. The method of claim 1, further comprising: placingthe unitary, substantially uniformly distributed transfer material andthe carrier material between a die and a heat dissipating element. 14.The method of claim 1, further comprising: heating the unitary,substantially uniformly distributed transfer material so as to breakconnecting elements coupling the plurality of geometric objects.
 15. Amachine, comprising: a transport element; and a pair of rollers, atleast one of which is to couple to the transport element, and at leastone of which comprises a roller pattern to form a corresponding patternin a solderable material, the roller pattern comprising an array ofelements arranged in a substantially repetitive manner.
 16. The machineof claim 15, wherein selected elements included in the array of elementsare interconnected by a plurality of connecting elements.
 17. Themachine of claim 15, wherein the array of elements includes a pluralityof substantially similar geometric objects.
 18. The machine of claim 15,wherein the array of elements are distributed on a grid pattern.
 19. Themachine of claim 15, wherein the array of elements comprises a pluralityof substantially similar geometric objects including regular geometricobjects.
 20. The machine of claim 19, wherein the array of elementscomprises a plurality of substantially similar geometric objectsincluding irregular geometric objects.